The desirability of a personal digital assistant (PDA), hand held computer, laptop computer, calculator, watch or the like powered by solar cells is readily apparent. Such a device might include, for example, a liquid crystal display and a solar cell array physically separate and removed from the display during the powering operation. That is, for example, the solar cell array may be included within a lid of the device, which in a closed condition covers the liquid crystal display and other operating elements of the device. Upon opening the lid the solar cell array within the lid becomes exposed to light and the liquid crystal display becomes exposed to the user, with the solar cell array then powering the liquid crystal display and/or charging a battery of the device. The solar cell array of course may power the internal electronics of the device.
As another example the display and solar cell array may be in fixed side-by-side relation.
While such approaches are workable, it will be seen that the exposed solar cell array and display take up a relatively large area as the device is operated.
A device of this general type is shown in U.S. Pat. No. 5,339,091 to Yamazaki et al, entitled "Paperless Portable Book", issued Aug. 16, 1994. As shown therein, the device includes a solar cell array which can receive sunlight from both sides of a lid so that power generation can continue with the lid opened or closed. However, with the lid of the device closed, the display and other elements of the device are blocked from view by the user.
Reference is made to U.S. Pat. No. 5,260,885 to Ma, entitled "Solar Power Operated Computer", issued Nov. 9, 1993. As disclosed therein, the device has an upper casing and a base, each having a solar cell assembly respectively hinged thereto to collect radiant energy. The device is in a compact stack in its folded up condition, and when unfolded the solar cell assemblies extend outward. Thus, the same problem arises.
U.S. Pat. No. 5,331,434 to Kikinis, entitled "Integrated Computer Scanning System", issued Jul. 19, 1994, discloses a photovoltaic film provided with a computer which allows the computer to be used as a scanner as well as a conventional computer. The photovoltaic cell is transparent and is applied directly to the display screen of the computer system, but does not generate power for the device.